Citing its Billionaires Index, Bloomberg reported Wednesday that the world’s 500 wealthiest people became almost $1 trillion richer ― that’s $1,000,000,000,000 ― in 2017, thanks largely to booming stock markets. For comparison, that’s over four times as much wealth as they gained last year.

Amazon founder Jeff Bezos, the world’s richest person, saw the biggest gain in wealth in 2017. He added $34.2 billion to his net worth, which now totals $100 billion.

Mark Zuckerberg, founder of Facebook, and Bernard Arnault, CEO of luxury goods company LVMH, also saw significant increases to their wealth this year. Zuckerberg, ranked by Bloomberg as the fifth richest person on Earth, added about $23 billion to his fortune. Arnault, ranked sixth, saw a $24.5 billion boost.

As of Tuesday, the 500 billionaires on Bloomberg’s wealthy index had a total net worth of $5.3 trillion ― up from $4.4 trillion in 2016. This year’s total is more than the gross domestic product of Japan or Germany, or that of the U.K. and France combined

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